Freezing-point depressant



Patented Oct. 9, 1928.

UNITED STATES SAMUEL ISERMANN, OF EAST ORANGE, NEW JERSEY, AND WALDEMAR:VERINET, 01

PATENT oFrrcE.

NEW YORK, N. Y.

FREEZING-roman nnrnnsssnr.

No Drawing.

The present invention relates to substances for'depressing the freezingpoint of water or aqueous solutions, particularly the waterused forcooling the cylinders of automobile or aeroplane engines.

In producing a suitable freezing point depressant many conditions arepresented, all of which must be in a measure satisfied, whereby theproblem is rendered a diflicult one and by no means as easy as mayappear at first sight. Various inorganic materials have been proposed,but as a rule these have been unsatisfactory due to the fact that uponcontinued use a substantial amount of corrosion is produced upon themetallic and non-metallic parts composing the circulatory system. In theorganic field, ethyl and methyl alcohol, for example, have been and arewidely used, but have the serious disadvantage that they are volatileunder conditions of use whereby they must be constantly replenished.This presents a real difficulty in that unless the mixture be testedfrom time to time (which is inconvenient) reliance cannot be placed uponthe mixture in the radiator not freezing. A

false sense of security may thus easily arise. In producing the improveddepressants of our invention we have endeavored to satisfy the followingconditions:

First: The absence of tendency to corrode the various materials commonlyused in the different parts of the engine cooling systems, such as iron,brass, aluminum, copper, solder, etc., and in addition absence oftendency to decompose and gum upon continued use.

Second A boiling point which is comparatively high, and such that ingeneral there will be practically no loss of the material throughevaporation, in case for some reason the engine becomes over heated fora considerable period the loss of the cooling solution will beprincipally withrespect to the water rather than the freezing point ofthe material that remains will still be within a safe region of thetemperature scale. I

Third: The flash point of the depressant should be high enough to permitof its being classified as non-inflammable by the Bureau ofCombu'stibles, thereby avoiding the strict regulations under whichinflammable matefreezing point.

depressant, whereby the Application filed July 9, 1925. Serial No.42,606.

rials are shipped and sold and so greatly re- .ducing the risk andexpense of selling.

Fourth: A not too high 'v1scos1ty of the coolin mixture at temperaturesnear the Otherwise the capacity of the pump may be exceeded and localoverheating may result. I

After long study and experimentation we have discovered freezing pointdepressants meeting the above requirementsin the soluble amids, the mostuseful being acetamid CH CONH andformamidHGONI-I Formamid is a liquidboiling at approximately 192 C., while actamid at roomtemperatures is asolid and boils at around 220 C. Both of the amids mentioned are solublein water in all proportions. In use, the propertions of both substancesto water, ma of course, be varied dependingupon the. reezing pointdesired for the cooling liquid. The following are examples of mlxturesvwhich may be employed, theparts in these and the 1 succeeding examplesbeing by weight.

' Acetamid 30 parts Water parts Freezing point of mixture -12 C.Formamid 30 parts Water 70 parts Freezing point of mixture i 15 C Inthe cfzse "of formamid a further increase in the proportion thereof towater resultsin a furt er depression of the freezing polnt untilequal'molecular quantities of formamid to water are reached, whereuponthe mixture has a freezing point of 50 C. This proportion corresponds to71.5 parts by weight of formamid to 28.5 parts by weight of water. Bothformamid and acetamid in addition to meeting the above requirements, arecharacaei'ized by non-inflammability, and great sta-.

i y- I We have discovered a further substance answering the requirementsabove set forth in hydroxy -2 keto-4.methyl pentane which has theformula. HOCKCHQ GH OOCH and is known commercially as diacetone alcohol.This substance may be regarded as a condensation product of acetone, andis a liquid havingja boiling point of from C. to C. iacetone alcohol maybe used alone or in combination with other depressants, such as theamids mentioned. A suitable mixture of diacetone alcohol and water is 40parts by weight of the former to 60 of the latter substance. When usedwith formamid, the following proportions will give a mixture having afreezing point of 125 C.

Parts by weight. Diacetone alcohol 15 Formamid Q 15 Water a. 70

Other alcohols (or acetals) which may be regarded as substantialequivalents of diacetone alcohol are diacetone glycerine, acetylacetone.

The substances we have described, particularly formamid and diacetonealcohol, have the'further advantage that they make possible the use ofglycerine and certain other substances of analogous composition such asethylene glycol, available as freezing point de ressants.

glycerine, for example, is an excellent freezing point depressant exceptfor the fact that at temperatures close to the freezing point theaqueous mixture becomes too viscous to be efficiently handled by thecirculating pumps commonly used in automobile work. Glycerine, moreover,is cheap and available in unlimited quantities. We have now discoveredthat the amide mentioned or diacetone alcohol or a mixture of thesematerials may be used in combination with glycerine and a mixtureproduced which will satisfy all the requirements including asatisfactory viscosity in aqueous solution at temperatures near t efreezing point. Thus a mixture of 80% by weight glycerine and 20%formamid or of diacetone alcohol (or mixture thereof) will give asatisfactory freezing point depressant for use in an desired quantity.Following are examp es of suitable mixtures:

Glycerine 15 parts Formamid 15 parts Water 70 parts Freezing point 14.5.0.

It will be understood that the freezing point depressants which we havedescribed may be used either alone or in combination with otherdepressants which have not been mentioned.

What we claim is:

1. A composition of matter for depressing the freezing point of water oran aqueous solution said composition comprising a soluble amid andglycerine. a

2. A composition of matter for depressing the freezing point of water oran aqueous solution said composition comprising a soluble amid,diacetone alcohol and glycerine.

3. A new composition of matter for depressing the freezing point ofwater or an aqueous solution said composition containing glycerine andcapable of being used in a quantity at least sufficient to depress thefreezing point of water 15 C. and having a maximum viscosity in aqueoussolution materially less than the nearest equivalent solution of pureglycerine.

4:. As a new composition of matter for depressing the freezing point ofwater or aque ous solution, glycerine and a substance reducing theviscosity of an aqueous solution of glycerine and having freezing pointdepressing properties sufiicient to yield an aqueous mixture having afreezing point of 15 C. and capable of being pum ed efficiently attemperatures immediately a ove the freezing point b the watercirculating pumping means 0 taining in automobile practice.

In testimony whereof we have aflixed our signatures to thisspecification.

SAMUEL ISERMANN. WALDEMAR VERNET.

